Suspension insulator



0d. 23, 1945. TRACY 2,387,480

SUSPENSION INSULATOR Filed March 27, 1944 Patented Oct. 23, 1945 UNITED STATES PATENT OFFICE SUSPENSION INSULATOR Atlee H. Tracy, Sarasota, Fla.

Application March 27, 1944, Serial No. 528,213

14 Claims.

This invention relates to suspension insulators such as are used in strings, that is, the'bolt or strain pin of one insulator is fastened to the socket or sustaining cap of the one below and a string of any desired number of insulator units is thus made up to provide in the aggregate sufficient insulation against the voltage of the line suspended thereby. The string of insulators is suspended from a supporting cross arm and the line wire is suspended from a fitting attached to the depending bottom insulator pin or bolt. Consequently such insulators have to carry heavy loads, particularly with the present-day heavy lines and long spans between supports.

, In the standard suspension insulator of today the recess in the porcelain insulator is tapered outwardly and downwardly so that the weight on the bolt tends to pull it out of the recess. Also, the metal cap which fits over the outside of the porcelain head to suspend the insulator is also outwardly tapered so that the weight carried tends to pull the insulator out of the metal cap. The insulator assembly is thus mechanically principled in the wrong way best to sustain the heavy loads to which it is subjected, particularly when it is considered that porcelain or any suitable insulating material which forms an important link in the chain is weakest in tension or shear.

It is an object of my invention to provide a suspension insulator in which all, or at least by far the largest portion, of the load-is supported by direct compression of the porcelain or other insulating material between the cap of the insulator and the insulator pin, thus adding materially to the mechanical strength of the insulator as compared to those now in general use in which the insulating material, or the bonding elements between the insulation and the mechanical assembly, is largely placed in shear rather than in direct compression,

A further object is the provision of novel suspension pin means and the method of assembling instead of throwing away the entire assembly as is common practice.

Other objects, features and advantages will appear from the detailed description and claims to follow in connection with the accompanying drawing, which shows by way of illustration and not of limitation an embodiment of the invention, and in which:

Fig. 1 is a vertical section of the insulator on the dividing plane between the cap halves;

Fig. 2 is a similar section at right angles to that of Fig. 1

' Fig. 3 is a horizontal cross-section through the neck of the insulator on the line 3-3 of Fig. 2; and

Fig. l is a side elevation of the cap showing the recessed edges of the half-caps in the lower parts for drainage purposes.

Referring to the drawing showing in detail the insulator assembly, the non-conducting, insulating and dielectric body of porcelain, glass or other suitable material has the usual or desired outstanding skirt portion I0, an enlarged head portion l l and a smaller neck portion l2.

The central depending pin preferably comprises two like parts or strips M of steel or suitable metal bars placed back to back to form the complete metal pin and having laterally projecting parts preferably by bending their upper ends I5 horizontally as shown and their lower ends l6 offset slightly to form a space between to receive the ears of the cap of the insulator below or the fitting of the line wire. These lower ends IB are shown slightly widened but of course may continue straight and are provided with a bolt hole I! to receive the connecting bolt 21. This type of connection between insulators is similar to the well-known clevis type. The upper half or part of this pin is embedded in a cement it, of suitable type, which adheres to and forms a bond with the metal of the pin and firmly holds its two parts together, and fills the recess in the head ll of the insulating body. This body of cement, which as will appear is surrounded by a suitable layer of yieldable material forming a lining of the recess in the insulating head, thus forms a cement head of the pin, and the pressure on the metal pin head due to the pull of the weight sustained thereby is distributed throughout the loacl-carrying surface of the cement head, that is, in this instance, throughout the lower substantially horizontal surface or circular area thereof.

In order readily to assemble these parts, and for other purposes, a bag l9'of rubber, rubberimpregnated fabric or other suitable moistureor water-proof material is employed which, when filled completely with cement, lines the inside of the recess in the insulating head H. One of the pin halves I4 is inserted in the empty bag and both are then inserted through the neck l2, which is large enough to permit their passage into the recess. The other half of the pin is then inserted, which can be readily done, and the whole, that is, the insulating body,-bag and pin halves, is inverted and placed in asuitable jig or form which holds the insulator and pin halves in their proper relative positions. The cement the entire empty space in the recess and around the pin as shown in the drawing.

drilling of holes and uncertainty of their location for complete drainage.

The tops of the half caps are made with upwardly extending ears 26 which together are adapted to fit in between the lower ends N5 of the pin halves Id of the insulator above, and arev secured therein by bolt 21 in a clevis-like manner, as seen in Fig. 2. Thus the insulators are readily connected together in chain formation with any desired number of insulators in the chain.

By this construction it is evident that substantially the whole load on the insulating member comes onto the horizontal portion 22 which therefore in direct compression and capable After the cement has set, the parts are removed from the jig or form in the positions shown'in the drawing and are ready for the completion of the assembly. The bag prevents the cement from bonding to the porcelain and provides a cushioning layer or lining of resilient or yieldable material between the porcelain and cement so that any differences in expansion in them due to temperature changes are cushioned.

The metal sustaining cap is made preferably in two similar semispherical, spheroidal or shelllike halves by stamping or otherwise, which when put together surround and enclose the head I I of the porcelain insulating member with the lower horizontal portions 2| underlying th corresponding horizontal portion 22 of the porcelain head II. A washer 23 of suitable yielding or re silient material is placed around the inside lower edge or horizontal part 2| of the cap, where it supports. the insulating member, to smooth out irregularities in the surfaces and to equalize the pressure. This washer may be in the substantially horizontal or load-bearing area only, but is shown extended down into the neck of the cap for ease in inserting and applying it, and to provide a cushion at this part which might be caused to bump into and strike the insulating member in assembling or otherwise if handled roughly.

The two half caps 20 are secured to ether when in place on the insulator by two semicircular rings 24. as shown in Fig. 3, havin inturned ends 25 which enter suitable holes formed in the half caps 20 in the lower part, said holes being midway between the edges of the halves. so that when in place the rings overlap the dividing line or plane between the half caps. These half rings are sufficiently spring-like so that when they are pushed into place the bent ends ride over the surface of the neck of the half caps until the ring reaches final position when these ends snap into the holes. Since the holes in the half caps are 90 from the meeting plane of the caps, any tendency for the two half caps to open is opposed by the tension of the rings. Bolts. rivets, welds, etc., are thus rendered unnecessary.

Since moisture is liable to get into or collect in the upper part of the cap, provision is made for draining same therefrom. This may be done in any desired way, as by suitably located drain holes through the cap walls, but preferably by slightly cutting back the lower part of the meeting edges of the half caps 20, as indicated in Fig. 4, from approximately the point 28 to the point 29 of the cap. These provide a narrow drainage slit on each side of the cap which will carry oiT the moisture from even the lowest point it can collect between the porcelain and cap. Such cutting-back can be done in the manufacture of the caps without extra trouble and renders unnecessary the of withstanding much greater loads than if the insulating. material were mainly in tension or in shear. The recesses in the porcelain insulator and in the sustaining cap are not outwardly ta-. pering but are so formed that the tendency of the contained parts is not to pull out of the recesses but to stay in. The provision of the multiple part pin and bag for assembling the same in the recessed head and providing the recess with a suitable lining and the metal pin with an enlarged head to distribute the pressure uniformly around the same, is important and useful results fiow therefrom. The bag method of lining the recess may be used in various types of insulators. The sustaining cap is simple, readily manufactured, efficient and of low cost. In case of break age of the porcelain, it may be discarded and the cap retained for use with another insulator.

While the invention has thu been described in detail, it .is apparent that various changes, alterations and modifications may be made therein without departing from the scope or principle of the same as set forth or intended to be set forth in the appended claims.

I claim;

1. A suspension insulator comprising an insulating body having a recessed head, a depending metal pin having an enlarged head in said recess, a bag of flexible material surrounding said pin head in said recess, and a filling of cement poured into said bagand filling the same and the recess around the pin and its head, said cement forming an enlarged headof the pin when the cement solidifies, and the bag forming a resilient layer between the wall of the recess and the cement head of the pin and preventing the cement from contactin the wall of the recess.

2. The method of attaching a strain pin in the recessed head of an insulating body for use in a suspension insulator, which consists in placing theend of the pin in a fiexible bag in the recess of the head, pouring cement in fiowable condition into the bag until the bag fills the recess and the cement surrounds the end of the pin, and permitting the cement to set, whereby the cement head of the pin fits the said recess and a yieldable lining is provided between the said pin head and the wall of the recess. 7

3. The method of attaching a metal strain pin in the recess of the head of an insulating body 'for a suspension insulator, the metal head of the complete pinbeing too large to pass through the neck leading to the recess, which consists in dividing the pin into a plurality of parts small enough to pass through the neck, putting one of the parts into a flexible bag of a size to fit the recess and inserting the two into the recess, then inserting the other part or parts of the pin in the bag and into position with the first part to form the complete pin, then pourin cement in flowable condition into the bag to fill the same and the recess and around the ends or the pin parts, and allowing the cement to harden and bond itself to the pin, whereby the pin parts are held together and a cement head fitting the recess is formed on the pin with a layer of flexible material between the cement pin head and the wall of the recess.

4. A suspension insulator comprising an insulating body having a recessed knob-like head, a depending strain pin secured in the recess of said head and a metal sustaining cap of 'shelllike globular form surrounding said head and supporting the same, said cap having suspending means at the top and being divided vertically into two halves to enable the same to be applied to the knob, the lower ends of said halves being curved outwardly and each half having an aperture intermediate its edges at the point of least diameter of each half, and semicircular clamping rings surrounding the halves at this point when the two are together, said rings having inwardly bent ends to snap into the said apertures to clamp and hold the two halves together when the parts are assembled.

5. A suspension insulator comprising an insulating body having an enlarged recessed head and a neck smaller in diameter, a depending pin having an enlarged head in said recess, a fiexible bag surrounding said pin head in said recess, and a filling of hardenable plastic material introduced into said bag and filling the same and the recess around the head end of the pin, said material forming an enlarged head of the pin when it hardens and the bag forming a lining of the recess.

6. A suspension insulator comprising an insulating body having an enlarged recessed head and a neck smaller in diameter, a multiple-part strain-pin having a head too large to pass through said neck when the parts thereof are assembled in final form but passable therethrough when disassembled, a flexible bag surrounding said assembled pin head in said recess, and a filling of hardenable plastic material introduced into said bag and filling the recess around the head end of the pin, said material forming an enlarged head of the assembled pin when it hardens and the bag forming a yieldable layer between said pin head and the wall of the recess.

7. A suspension insulator comprising an insulating body having a flattened knob-like recessed head with a neck restricted in diameter, the lower load-carrying wall portion of said head being horizontal, a depending strain-pin having an enlarged head in said recess, a flexible bag surrounding said pin head in said recess, a filling of hardenable plastic material introduced into said bag and forming an enlarged head for the pin when it hardens, said enlarged head having a horizontal portion bearing on the inside of the corresponding wall portion of the recessed head, said bag forming a lining between the said two horizontal portions, and a metal shell-like sustaining cap encompassing said knob-like head and extending horizontally under said horizontal portion of the recessed head to sustain the same, the said cap being otherwise free of sustaining connection with the recessed head, and a layer of flexible material between the two last-named horizontal portions.

8. A suspension insulator comprising an insulating body having an enlarged recessed head with restricted neck and horizontal lower loadbearing wall portion, a depending strain-pin having an enlarged head in said recess, a flexible bag. surrounding said pin head in said recess, a filling of hardenable plastic material introduced into said bag and filling the same around the pin head, saidmaterial when it hardens forming an enlarged head of said pin having a horizontal bearing portion over said horizontal wall portion of the recess, said bag forming a lining between said horizontal bearing portions, a globular sustaining cap having means to suspend it from above, said cap being larger inside than said recessed head but surrounding same and having a lower horizontal load-sustaining portion beneath the horizontal portion of the recessed head to carry the load thereon, said cap being divided axially into separate parts to permit fitting the same over and around said head, means to secure said parts together around the head, said parts engaging each other edge to edge when so secured together to prevent them from being clamped upon and engaging the head except at said lower horizontal portion, and a lining between said last two horizontal portions, whereby the load on the insulator is carried through said horizontal portion of the head and the latter is in compression thereby,

9. A suspension insulator comprising an insulating body having an enlarged knob-like recessed head with a restricted neck, the lower load-bearing portion of the wall of the recess being horizontal, a strain-pin for the insulator having a head extending over said horizontal wall portion of the recess and bearing thereon to carry the load, and a hollow metal spheroidal sustaining cap surrounding and enclosing said insulating head and having its lower wall portion extending horizontally under said horizontal wall portion of said head to sustain the same, said cap being larger inside than the said insulating head and mechanically free therefrom except at said horizontal portion, whereby the load is substantially limited to said horizontal portions and places the insulating wall under compression only.

10. A suspension insulator comprising an insulating body having a knob-like recessed head with a lower horizontal portion, a strain-pin having a head within the recess of the head, said head having a load-supporting portion bearing on said horizontal portion of the recess wall, a hollow globular sustaining cap for the insulator encompassing the head and having its lower portion supporting the insulating head at said horizontal portion, said cap being larger inside than the said insulator head and consisting of sections divided axially and secured together edge to edge to hold them together and to prevent them from being clamped tightly upon the head, said insulating head being mechanically free in the cap and supportingly engaging same only at the horizontal portion, the lower part of the cap being provided with drainage openings.

11. A suspension insulator comprising an insulating body having an enlarged recessed head with a re-entrant horizontal lower portion, a depending strain-pin having a head in said recess bearing on said horizontal portion, a metal shell-like sustaining cap enclosing said recessed head, said cap being larger inside than the head and extending under said horizontal portion thereof to receive the load thereof and curving downwardly along the neck of the insulating head, a lining washer between the horizontal portions of the cap and recessed head and extend ing downwardly around the said neck, said cap being divided axially into a plurality of sections, and means for securing said sections together edge to edge about the said recessed head to avoid clamping tightly upon the same, one of said meeting edges being recessed at the lower part to provide a condensate drainage opening from the interior of the cap, said drainage opening extending upwardly above the said washer.

12. The method of attaching a supporting pin in the recess of an insulator and lining the same which comprises placing the end of the pin in a flexible bag in the recess of the insulator, introducing a hardenable plastic material into the bag to fill the same and around the pin, and permitting the material to harden, whereby the material forms a part of the pin head and the bag lines the recess.

13.,The method of attaching a strain-pin in the recess of the head of an insulating body for a suspension insulator, the head of Which pin is too large to pass through th opening leading to the recess, which consists in dividing the pin into a plurality of parts, inserting said parts in a flexible bag in the-recess of the'head and suitably assembling them therein, introducing a hardenable plastic material into the bag to fill the recess and around the pin, and allowing said material to harden.

14. A suspension insulator comprising an insulating body having a recessed knob-like head and a neck smaller in diameter, a depending strain-pin secured in the recess of the head, a metal sustaining cap of globular form surrounding said head and extending beneath the same to support it, said cap being divided vertically into two .halves, each half having an upwardly extending ear at the top, which fit together to form a suspending lug for the cap and insulator, said ears'being apertured to receive a bolt therethrough to clamp the halves together at the top,

the lower ends of said halves being curved downwardly and outwardly adjacent the neck of the insulator, and securing means extending around the restricted portion of the halves at the neck to secure said halves together at the bottom.

' A'ILEE H. TRACY; 

